Rolling bearings such as angular ball bearings are used for support of shafts which rotate at relatively high speed such as various types of spindles used on working tools. As lubricating methods for lubricating rolling bearings for supporting such spindles which rotate at high speed, conventionally, an oil-air lubricating method has mainly been used in many cases.
The oil-air lubricating method is a method for blowing a minute amount of lubricating oil which is intermittently supplied towards the rolling bearing through piping by virtue of compressed air, and in this method, since the lubricating oil is supplied to the bearing by being caused to forcibly pass through an air curtain formed around the rolling bearing which rotates at highs speed, the compressed air is used as a so-called carrier.
In the oil-air lubricating method like this, an oil-air lubricating device and a mixing valve, as well as a compressor and external piping are necessary externally of the spindle or the like in which the bearing, which is an object for lubrication, is incorporated, and in addition to this, passageways for oil and air need to be formed in an interior of the spindle or the like. This causes problems that the production costs are increased and that the noise level is increased due to the use of compressed air.
With a view to solving the problems, there have been proposed rolling bearing devices in which a lubricating oil supply mechanism is incorporated in an interior of a rolling bearing (refer, for example, to Patent Document Nos. 1, 2). A practical configuration example of the rolling bearing which a lubricating oil supply mechanism is incorporated incorporates therein is shown in FIGS. 10 and 11. FIG. 10 is an axially parallel sectional view, and FIG. 11 is a front view which results when viewed from the right in FIG. 10. In this example, a rolling bearing includes an inner ring 51, an outer ring 52 and a plurality of rolling elements 53 disposed in such a manner as to freely roll in such a state that they are held at constant intervals in a circumferential direction between the inner ring 51 and the outer ring 52 by a cage 54, and an oil supply unit made up of a tank 55 for storing therein lubricating oil, a pump 56 for sucking out to discharge the lubricating oil stored in the tank 55, a nozzle 57 mounted at a discharge port of the pump 56 and made to extend to the vicinity of the rolling element 53 within an annular space defined between the inner ring 51 and the outer ring 52 in such a manner as to be made to open thereat and a drive circuit 58 including a power supply battery for the pump 56 is constructed to be fixed to an inner circumferential surface of a stationary ring, for example, the outer ring 52 of the rolling bearing, so as to supply an extremely minute amount, for example, several tens of nl/min, of lubricating oil from the opening at a distal end of the nozzle 57 to the inside of an air curtain formed when the rolling bearing rotates.
According to the proposed techniques, since the lubricating oil is supplied to the inside of the air curtain generated when the rolling bearing rotates, compressed air, which is required as a carrier in the case of the oil-air lubricating method, is no longer necessary, and hence, the noise problem can be solved, and additionally, the compressor, the oil-air lubricating unit, and furthermore, the external piping and the internal piping are also no longer necessary, which makes the proposed techniques advantageous in costs, as well.    Patent Document No. 1: JP-A-2004-108388    Patent Document No. 2: JP-A-2004-316707